I've recently switched to using Gmail via IMAP in Mail.app on Lion, and I've mostly got it configured to do what I want. However, there's one annoyance I haven't been able to fix yet. Because of Gmail's peculiarities, I have at least 2 copies of every message in my inbox - 1 in my inbox, 1 in the All Mail folder (Gmail's archive). This isn't a big deal, except that Mail seems to like to announce this fact for every message that's got a duplicate, like so:

I'm aware that in Gmail's IMAP settings you can disable the All Mail folder from showing up on the client, but I like having it around for search purposes (and it doesn't solve the problem of duplicates when you label something). Is there any way, short of disabling All Mail, to get rid of this duplicate detection? Or should I just work on being less annoyed by superfluous messages?

I also have the exact same problem and concern (discussions.apple.com/message/16823327). I was hoping that there was a Terminal command that could be issued to disable this annoying "feature". I want to be able to see ALL messages, including those so-called duplicates (which, in my case, are all false positives).
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user14184Nov 26 '11 at 19:34

You could edit the localization files so that "2 duplicates" reads "2 other labels" instead. :-)
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Kevin ReidDec 3 '11 at 17:54